Open AccessEffect of blanching pretreatment and microwave-vacuum drying on drying kinetics and physicochemical properties of purple-fleshed sweet potato
Author(s) -
Sigit Uji Marzuki,
Yudi Pranoto,
Tabkrich Khumsap,
Lien Thi Phuong Nguyen
Publication year - 2020
Publication title -
journal of food science and technology/journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.656
H-Index - 68
eISSN - 0975-8402
pISSN - 0022-1155
DOI - 10.1007/s13197-020-04789-5
Subject(s) - blanching , microwave , thermal diffusivity , chemistry , dehydration , kinetics , water content , materials science , moisture , water activity , vacuum drying , freeze drying , food science , composite material , chromatography , biochemistry , physics , geotechnical engineering , quantum mechanics , engineering
In this study, drying kinetics and quality of purple-fleshed sweet potato (PFSP) subjected to microwave-vacuum drying were investigated. The effects of hot water and steam blanching pretreatment on physicochemical characteristics of the dried products were also considered. The samples were dehydrated in a custom-made microwave-vacuum system at different power levels including 450, 600 and 850 W. Hot air drying at 70 °C was also conducted for comparison. The results showed that drying time of PFSP under microwave-vacuum conditions ranged from 6 to 12 min, significantly reduced as compared to that of hot air drying (600 min). The improvement of drying rate was also evidenced by increased effective moisture diffusivity (2.22 × 10 -7 -4.05 × 10 -7 m 2 /s) of the samples. Drying kinetics of PFSP was best fitted by Page and logarithmic model with R 2 ranging from 0.991 to 0.998, and RMSE from 0.016 to 0.030. PFSP dried under microwave-vacuum condition had lower water absorption index and swelling capacity than hot air drying. Color, antioxidant activity and total phenolic content of dried PFSP were also improved under microwave-vacuum drying. The effects of blanching pretreatment on quality of dried PFSP were more dominant in hot air than microwave-vacuum dried samples.